1. Field of the Invention
This invention relates to electronic part mounting boards and to semiconductor devices using such electronic part mounting board, and more particularly relates to an electronic part mounting board and to a semiconductor device using the same, having a board fixing pin by which a circuit board for mounting the electronic part may be supported with respect to a lead frame.
2. Description of the Related Art
In recent years, semiconductor elements have been further advanced in their high density construction and it is increasingly more difficult to mount a semiconductor element directly on a printed wiring board or the like to construct various electronic equipment. In recent practice, thus, a semiconductor element is previously mounted for example on a board for mounting the electronic part to form a semiconductor device and such semiconductor device is then electrically connected to a printed wiring board using a surface mount technology or the like. Accordingly, proposals have been made of various boards for mounting electronic parts and of semiconductor devices using the same.
For example, for a semiconductor device internally having an electronic part mounting board integrating a lead frame and a printed wiring board, a circuit board with an electronic part attached thereto must be supported on the lead frame during the fabrication process of the semiconductor device, to connect the electronic part to leads of the lead frame by means of wire bonding. According to a conventional technology disclosed in Japanese Patent Laid-Open Publication No.59-98545, supporting of a circuit board on a lead frame is performed by joining the lead terminals of the lead frame to the conductive layer on the circuit board by means of solder or Au/Sn soldering. Further, in the method disclosed in Japanese Patent Laid Open Publication No.62-133791, the lead of a lead frame is inserted into a through hole formed on a circuit board and the terminal end of the lead is bent to be secured to the through hole by means of caulking.
To use solder or soldering in coupling the circuit board and the lead frame, the junction must be heated at least to 200.degree. C. An ordinarily used board made of a resin may thus be deteriorated due to heat, or an internal stress may occur therein due to the fact that the thermal balance between the circuit board and the lead frame cannot be maintained, resulting in such problems as that fault occurs at the time of mounting the electronic part and that the reliability is reduced of the finished product. Further, in the case where the terminal end of the lead is bent to be caulked, since an individual lead may be integrally formed only at one side of the circuit board, though readily applied to an electronic part mounting board or a semiconductor device of the single in-line package (SIP) type, this bonding method is difficult to be applied to those of other types whereby it cannot be widely used. In addition, since the lead is forcibly caulked to the through hole, a stress is applied to the plating of the through hole to reduce the reliability of the connected portion.